NEFilterDataProvider Filtering Traffic to 127.0.0.1 Breaks Maven Build in IntelliJ IDEA

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     When filtering traffic to localhost (127.0.0.1), it causes Maven repository synchronization to fail in IntelliJ IDEA. However, Maven works correctly when local traffic is not filtered. I will provide a minimal code reproduction below.

- (void)startFilterWithCompletionHandler:(void (^)(NSError *error))completionHandler {
    // Add code to initialize the filter

    NSMutableArray *rules = [NSMutableArray array];
    NENetworkRule * rule = [[NENetworkRule alloc] initWithRemoteNetwork:nil remotePrefix:0 localNetwork:nil localPrefix:0 protocol:NENetworkRuleProtocolTCP direction:NETrafficDirectionAny];
    [rules addObject:[[NEFilterRule alloc]initWithNetworkRule:rule action:NEFilterActionFilterData]];

    rule = [[NENetworkRule alloc] initWithRemoteNetwork:nil remotePrefix:0 localNetwork:nil localPrefix:0 protocol:NENetworkRuleProtocolUDP direction:NETrafficDirectionAny];
    [rules addObject:[[NEFilterRule alloc]initWithNetworkRule:rule action:NEFilterActionFilterData]];

    NWHostEndpoint *hostEndpointIpv4 = [NWHostEndpoint endpointWithHostname:@"127.0.0.1" port:@"0"];
    NENetworkRule *localHostRuleIpv4 = [[NENetworkRule alloc] initWithRemoteNetwork:hostEndpointIpv4
                                                                         remotePrefix:32
                                                                         localNetwork:hostEndpointIpv4
                                                                         localPrefix:32
                                                                           protocol:NENetworkRuleProtocolAny
                                                                          direction:NETrafficDirectionAny];
    [rules addObject:[[NEFilterRule alloc]initWithNetworkRule:localHostRuleIpv4 action:NEFilterActionFilterData]];
    
    
    NEFilterSettings *filterSetting = [[NEFilterSettings alloc] initWithRules:rules defaultAction:NEFilterActionAllow];
    

    
    [self applySettings:filterSetting completionHandler:^(NSError * _Nullable error) {
            if (error) {
                NSLog(@"Failed to apply filter settring: %@", error.localizedDescription);
            }
            completionHandler(error);
    }];
}

Maven Sync error: iwEdAqNwbmcDAQTRCNQF0QCaBrBE2Ouc982L8gidAXMk6LMAB9MAAAAAsHxy5QgACaJpbQoAC9IAAoOK.png

System Log:

默认	17:35:13.184509+0800	kernel	cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so 3bb6402f58a82e37 - flags 0x800840 0x80> lport 63166 fport 29735 laddr 127.0.0.1 faddr 127.0.0.1
默认	17:35:13.184510+0800	kernel	cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so d6dde374c8cb613b - flags 0x800840 0x80> lport 63165 fport 29735 laddr 127.0.0.1 faddr 127.0.0.1
默认	17:35:13.529546+0800	kernel	cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so cc915e74ba29f8cb - flags 0x800840 0x80> lport 63169 fport 39066 laddr 127.0.0.1 faddr 127.0.0.1
默认	17:35:13.529546+0800	kernel	cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so 2e15c3e54ebcc45 - flags 0x800840 0x80> lport 63168 fport 39066 laddr 127.0.0.1 faddr 127.0.0.1
默认	17:35:14.046094+0800	kernel	cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so 71f6d3a53472131f - flags 0x800840 0x80> lport 63172 fport 53241 laddr 127.0.0.1 faddr 127.0.0.1
默认	17:35:14.046145+0800	kernel	cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so c88a367c9717185b - flags 0x800840 0x80> lport 63171 fport 53241 laddr 127.0.0.1 faddr 127.0.0.1

Environment Details: Operating System: macOS 15.5 (Sequoia) IDE: IntelliJ IDEA 2025.1 Relevant Technology: NEFilterDataProvider (Network Extension)

I have found reports of similar problems online：

https://discussionschinese.apple.com/thread/255270330?sortBy=rank
https://blog.csdn.net/weixin_42339552/article/details/137402307

They all seem to be caused by network extension。

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